Process for making galvanized articles



2 Sheets-Sheet l Q. m, nl@ ma.

June' 16, 1942.

A. F. BRADLEY PROCESS FOR MAKING GALVANIZED lARTICLES Filed March a.'195s June 16, 1942. A. F. BRADLEY PROCESS FOR MAKING GALVANIZED ARTICLESFiled March 8, 1959 2 Sheets-Sheet 2 Vfv Patented June 1.6, 1942 PROCESSFOR MAKING GALVANIZED ARTICLES Albert F. Bradley, Sterling, Ill.,assgnor to Northwestern Steel and Wire Company, Sterling, Ill., acorporation of Illinois Application Maren s, 1939, serial 10.260,543

' (ci. :a1-10.3)

2 Claims.

This invention relates to a method of and apparatus for annealing andgalvanizing metal articles such as steel or iron wire, -to produce abetter zinc coating o`n annealed wire than has hitherto been attained.

More specifically the invention relates to the inside annealing of colddrawn wire, to retain some of the strain and/or some residual pattern ofthe original drawn structure on the outside of the wire, followed by agalvanizing of the wire to produce a better coating due to the retainedsurface properties of the wire.

While the invention will hereinafter be spe-- cically described asapplied to wire, it should be understood that it is not limited to suchapplication.

I have found that steel or iron wire which has been cold-drawn and notsubsequently annealed' will, when immersed in a bath of molten zinc,acquire a coating of given thickness in less time and the coating willbe stronger and more adherent than when a coating of similar thicknessis applied in a similar manner to annealed wire. The reason for this isnot known, but it is thought by someto be due to changes which lythroughoutits cross-section while continually allowing its surface tolose heat by radiation, thus making the interior of the wire hotter thanthe surface. In this manner, the interior of the wire is heated Well upinto the range of temperatures at which relief of internal strains andrecrystallization can take place while the surface of the wire is heatedto a temperature just short of this range. The surface of the wiretherefore retains at least some of the strains and surface patternimparted thereto during the cold-drawing operation.

It may be that in the process as actually car-V ried out the surface ofthe wire is also heated up into the annealing temperature range, but ifthat is the case the surface is still much less hot than the interior ofthe wire and is hot for a much shorter interval of time. At any rate,the momentary heating of the surface of the Wire to a temperatureconsiderably lower than that necessary to thoroughly anneal the interiordoes'not materially lessen its ability to take 'galvanizing Whatever maybe the correct explanation of the Process which I have discovered, thefact remains that my discovery results in a new and improved process forgalvanizing wire.

Another result lof my discovery is annealed wire with a more adherentgalvanizing than has hitherto been produced.

In addition, the annealing process used in this invention producesgreater'softness andductility than is obtained in customary annealingpractice. In order to obtain the same softness according to usualannealing practice it would be necessary to use a very high temperatureor a longer annealing time, which would result in heavy scale or oxideand a consequent increase in cost of pickling and loss of weight ofsteel. or iron.

The means which I have found most convenient for generating heat in theinterior of a wire is an electric current, preferably direct current oralternating current caused to flow along a length of the wire. Ordinary6Q cycle alternating current is satisfactory. One of the most con`venient Ways of causing an electric current to flow through a wire andheat it to the proper temperature is to pull the wire along in contactwith a pair of spaced rollers maintained at different electricpotentials and adjusting the potential difference, the distance betweenthe rollers or the rate of movement of the wire to give thetemperaturedesired.

In order to carry out the process which I have discovered, I haveinvented an improved device for heating wire by electricity, and I havealso invented a 'new combination of wire-drawing mechanism, electricannealing device and galvanizing apparatus which operates oncontinuou'slyvmoving wire.

An object of the invention is to anneal the interior of cold workedmetal articles Without destroying the cold worked surfaces and to coatthese surfaces with a protective meta1.

A specific object of the invention is to anneal the interior of colddrawn ferrous metal wire while retaining at least some of the strain andresidual metal pattern in the surface of the wire and to then galvanizesaid wire.

One of the further objects of my invention is to provide an apparatusfor conveniently and economically carrying out my process.

Another object of my invention is to provide an apparatus for producingelectrically annealed. drawn wire in which the annealing device is ar-55 ranged to continually receive wire from a wiredrawing machine so thatthe wire reaching the annealing device will be heated from just havingbeen drawn and will require less electrical energy than otherwise toraise it to the desired temperature.

Another object of my invention is to provide an electric annealingdevice through which wire may be drawn continuously and which willautomatically stop the electric current in the wire in case the wirebreaks.

Another object of my invention is to provide a multiple electricannealing device through which a large number of wires may be drawncontinuously and simultaneously and wherein each may be rapidly heatedto an annealing temperature.

Other objects of my invention will appear from tion of the pickling andgalvanizing portion of the apparatus;

Figure 4 is a broken plan view of the annealing portion of the apparatusand part of the pickling and galvanizing portion of the apparatus; v

Figure 5 is a fragmentary enlarged side view, partly in section, of apart of the annealing portion of the apparatus;

Figure 6 is a fragmentary enlarged back view of part of the annealingportion of the apparatus as seen from the line VI-VI of Figure 5,looking in the direction of the arrows.

The form of the apparatusshown in the drawings is arranged tocontinuously draamal and galvamze a number ofxfwires'V II 'which passthrough the apparatus in parallel paths. In the particular apparatusillustrated, forty-eight wires II are operated on simultaneously, butobviously, the apparatus may be designed to handle any number. Theapparatus comprises a wire-drawing mechanism I 2, an electric wireannealing device I3, a pickle tank I4, a. rinse tank I5, a ux tank I6, agalvanizing tankl1, and take-up reels I8 for winding up the finishedwire and drawing it through the annealing device I3 and the varioustanks I4, I5, I6 and I1. 'Ihe various pieces of apparatus are arrangedone after the other so that the wires Il, entering the wiredrawingmechanism as rod stock or heavy wire I9, can pass directly through theentire apparatus in the minimum time and emerge as .finished annealedwire.

'I'he wire-drawing mechanism I2, which is shown diagrammatically inFigure 2, comprises a die 2l for each wire and one or more wiredrawingdrums 22 for pulling the wire through the dies. There may be a singlehorizontal drum or a plurality of narrow horizontal drums, one for eachwire, mounted on a single shaft, or any other arrangement that willhandle the number of wires for which the apparatus is designed. Also,while I have diagrammatically illustrated v a single draw machine, thedrawing mechanism may comprise a multiple draw machine if a largereduction is required to produce the desired gauge vleaving the drumwill keep it wound tightly enough around the drum to enable the drum todraw it through the die.

From the wire-drawing mechanism I2, the

wires Il pass to the electric* annealing device I3 ,which comprises atable or'frame 23 carrying a plurality of grooved -rollersfor sheaves24, 25, 26, 21 and 28 arranged so that the wires II can pass over thefirst, third and fifth sheaves 2'4, 26 and 28 and under the second andfourth sheaves 25 and 21. The shafts 29 and 3| on which the second andfourth sheaves 25 and 21 are mounted are provided' with contact discs32and 33. 'I'he peripheries of the contact discs 32 and 33 are engaged byspring pressed brushes 34 and 35 connected lby wires 36' and 31 to thesecondary of a suitable transformer 38 which causes a current to owbetween the two sheaves or roll-y ers 25 and 21. In order to cause thiscurrent to flow in the wires I I and heat them, theshafts 29 and 3| ofthe two contact sheaves 25 and 21 are carried in bearings or .brackets4I and 42 separated from the frame 23 by suitable electrical insulation43 and 44 so that there is no path for the current except Athrough thewires II.

'I'he sheaves 24 and 28 at the ends of the annealing device are carriedby brackets 45 and 46 which may be separated from the frame 23 byelectrical insulation 41 and 48, in a manner simy ilar to that employedin connection with the contact sheave bearings 4I and 42, in order toprevent sneak currents from flowing through the -frame 23. The centralsheave 26 between the two contact sheaves is carried -by a pair ofbrackets 49, which need not beinsulated, but which are made verticallyadjustable by -being clamped to the frame 23 .by bolts 5I passingthrough slots4 52 in the brackets 49. 'Ihis allows the central sheave26, which is under the wires I I, to be raised or lowered to a positioninwhich the Wires make good contact with the contact sheaves 25 and 21at either side of the central sheave 26.

The bracket 45 which carries the irst sheave 24 of the annealing devicealso carries a series of arms 53 above-the wires Il, one arm for eachwire. Each arm 53 is pivoted to the bracket 45 so that it can swingvertically, and it-carries its own individual grooved wheel 54 whichrests on top -of one of the wires II between the first sheave 24 and thefirst contact sheave 25. Each arm 53 and grooved wheel 54 is providedwith a leaf spring 55 which presses the wheel 54 down lightly on thewire II so that, if any one of the wires breaks, that wire isimmediately pushed down out of contact with the contact sheave 25 andthe current through it is broken, thus .pre-

venting it from overheating.

From the last sheave 28 of the annealing device, the wire Il passes downinto and out of` wire Il through the preceding parts of the apparatus ata steady rate.

The exact ratev at which the' wire moves is not critical, as theapparatus can be designed to properly treat the wire while moving at'anyspeed which would be commercially desirable for use with thewire-drawing machines or other por-k tions of the apparatus. Anextremely slow wire speed would make the annealing time too long andatthe same time make` the production rate undesirably'low. I have foundthat wire speeds of 42 It. a minute give goed results when ernployedwith an annealing device in which the contact sheaves are three feetapart, this combination providing an annealing time of between four andfive seconds. Higher or lower wire speeds may be employed, and theannealing time may be shorter or longer than that given, but longannealing times should be avoided because the success of the processapparently depends on the incomplete annealing of the surface of thewire. With lower wire speeds, the annealing time can be kept down byplacing the contact sheaves closer together and lowering the electricalpotential difference between them.

In practice, it has been found to be suilicient` to provide some means.such as a multi-tap transformer, of making small changes in thepotential diierence applied to the contact sheaves and to keep thecontact sheave spacing and wire speed constant while varying thepotential difference until the best results were secured.

lIt will, ol? course, -he understood that various details ofconstruction may be varied through a wide range without departing fromthe principles of this invention and it is, therefore, not the purposeto limit the patent granted hereon otherwise than necessitated by thescope of the appended claims.

I claim as my invention: Y

1- In a process of making metal articles including an initial coldworking step and a subsequent coating of a cold Iworked article with aprotective metal, the improvement comprising an intermediate stepincluding disposing a cold worked article so as to permit its surface toradiate heat freely and generating heat within the cold worked articleat suchA a rate and for such a time in relation to the rate ofdissipation of heat from the surface of the article as to raise theinterior of the article but not the exterior of the article to atemperature within the annealing range for a time suilicient to removesubstantially completely the cold worked structure of the article-onlyin the interior thereof.

2- The continuous process of making galvanized annealed wire whichcomprises drawing wire stock through a reducing die, continuouslypassing the resulting wire through a heating zone, flowing an electriccurrent through the traveling wire in the heating zone, dissipating heatgenerated by said electric current from the wire surface, adjusting themagnitude of said; current and the rate of heat dissipation to maintain-the temperature of the interior of said wire in the recrystallization-range and the temperature of the exterior of the wire below said range,and continuously passing the heat treated wire through a bath of moltenzinc.

ALBERT F. BRADLEY.

